I think it’s fair to say that the majority of peer reviewed research re global warming and its causes supports the hypothesis that man plays a substantial role, at the very least a role that man has the ability to have a measurable effect. Now it is possible that these scientists are subject to group think and that the opposing scientists, a minority, are correct. It’s also quite clear that the science is evolving and we don’t know as much as we will know in 10 or 20 years. But if you are responsible for making policy and you’re hearing from a large segment of the scientific community that unless substantial action is taken fairly soon a tipping point might be reached with potentially catastrophic consequences then I think that you are under a great deal of pressure to enact mitigating policies.
If I were judge the motivations of the IPCC and the MIT scientists to the motivations of Senator Inhofe I’d side with the former but that's just me. This is not to say cap and trade is the best policy.
The article below describes some recent work by MIT scientists.